Optoelectronic devices, e.g. light-emitting diodes, include an active layer to emit light of specific wavelength. The active layer can be a semiconductor epitaxial structure, such as homostructure, single heterostructure (SH), double heterostructure (DH), multiple quantum well (MQW), or the likes. Because the light-emitting diodes have excellent optoelectronic properties: low power consumption, long lifetime, high impact resistance, small volume, fast response rate, and stable emission wavelength, they are usually applied in household appliances, instrumental indicators, light sources of optoelectronic products, optoelectronic communications, and the likes.